Summary
Inputs of acid deposition are firmly linked to changes in tree nutrition, reductions in woody growth, and increases in mortality for numerous tree species. Although this vulnerability to decline is well established, identifying specific locations most at risk is difficult because of the great spatial variation across the region in pollutant deposition levels, soil nutrition, species composition and other factors. Identifying specific locations where trees are most at risk of damage would help managers better monitor and remediate the impacts of acid deposition. A Forest Service scientist and his partners used a computer model that simulated nutrient cycling and acid deposition inputs for every 30 m parcel across Vermont and New Hampshire to identify locations where pollution inputs likely exceeded biological thresholds and resulted in reduced tree growth. Model results were field tested by relating model findings to radial growth measurements obtained from red spruce increment cores from 441 trees at 35 locations. Model results successfully identified locations where acid deposition reduced red spruce growth over the last 60 years. This finding suggests that the model and associated maps could be helpful in identifying forest stands most vulnerable to acid deposition-induced damage that may warrant special monitoring and management.
